使用 decodeByteArray 转换位图：显示黑色图像和 LogCat 显示 skimagedecoder 工厂返回 null

Question

我正在尝试从每 5 秒发送一次图像的远程服务器接收图像。现在，在 Android 端，我正在使用 decodeByteArray() 将其转换为位图。运行时，有时会在屏幕上显示图像，有时会显示黑屏，LogCat 显示skimagedecoder 工厂返回null。我不知道问题是什么。

这是我的代码：

public class connection extends AsyncTask {

    @Override
    protected Object doInBackground(Object... arg0) {

        int i = 0;
        try {
            clientSocket = new Socket("134.129.125.126", 8080);
            input = clientSocket.getInputStream();

        } catch (UnknownHostException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        while (true) {
            data = new byte[2048 * 2048];

            try {
                read = input.read(data, 0, data.length);

                System.out.println("getInputStream()");
                bitmap = BitmapFactory.decodeByteArray(data, 0, read);

                System.out.println("deco");

            } catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
                System.out.println(e);
            }
            runOnUiThread(new Runnable() {
                public void run() {

                    image.setImageBitmap(bitmap);
                    System.out.println("setImage at less than 500");

                }
            });
        }

    }

}

更新 现在，尝试从服务器接收图像的大小，并使其成为正确大小的字节数组。然后decodeByteArray()，又变成Factory返回Null。这是我修改后的代码：

public class connection extends AsyncTask {

        @Override
        protected Object doInBackground(Object... arg0) {

            try {
                clientSocket = new Socket("134.129.125.126", 8080);
                System.out.println("client connect to server");
                input = clientSocket.getInputStream();
                System.out.println("getinputstream");
            } catch (UnknownHostException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            // while (true) {
            int totalBytesRead = 0;
            int chunkSize = 0;
            int tempRead = 0;
            String msg = null;
            // byte[] data = null;
            byte[] tempByte = new byte[1024 * 1024 * 4];
            try {
                tempRead = input.read(tempByte);
                System.out.println("read:" + tempRead);

            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            if (tempRead < 2000) {
                String message = new String(tempByte, 0, tempRead);
                msg = message.substring(0, 6);
                System.out.println("message head:" + msg);
                byteSize = Integer.parseInt(msg);
                System.out.println("ByteSize:" + byteSize);
                data = new byte[byteSize];
            }

            try {

                while (chunkSize > -1) {
                    System.out.println("data length:" + data.length);
                    chunkSize = input.read(data, totalBytesRead, data.length
                            - totalBytesRead);
                    System.out.println("chunkSize is " + chunkSize);
                    totalBytesRead += chunkSize;
                    System.out.println("Total byte read " + totalBytesRead);
                    if (totalBytesRead == data.length) {
                        if (input.read() != -1) {
                            // error, the file is larger than our buffer
                            throw new RuntimeException("Buffer overflow error!");
                        }

                    }
                }
            } catch (Exception e) {

            }

            bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

            System.out.println("deco");

            runOnUiThread(new Runnable() {
                public void run() {

                    image.setImageBitmap(bitmap);
                    System.out.println("setImage at less than 500");

                }
            });

            return null;
        }

    }

Answer 1

一方面，不能保证您的读取命令正在读取整个图像。 InputStreams 倾向于读取当前可用的字节数，这可能会或可能不会直到文件末尾，这取决于实现。

您应该继续读入您的字节数组，直到从input.read() 返回的值是-1。这显然需要对一些循环逻辑进行返工，直到您返回 -1 并有一个变量来跟踪读取的总字节数作为所有读取调用的总和。

例如，从流中读取所有内容

int totalBytesRead = 0;
int chunkSize = 0;
byte[] fileBuffer = new byte[4 * 1024 * 1024];  // 4MB buffer

while (chunkSize > -1) {
    chunkSize = inputStream.read(fileBuffer, totalBytesRead, fileBuffer.length - totalBytesRead);
    totalBytesRead += chunkSize;
    if (totalBytesRead == fileBuffer.length) {
        if (inputStream.read() != -1) {
            // error, the file is larger than our buffer
            throw new RuntimeException("Buffer overflow error!");
        }
    }
}